How difficult is it to make a micro refrigerator?

This paper describes how the entropy generation rate changes at each component in a vapor compression refrigerator as the system scale is decreased. A so-called micro refrigerator composed of all components in micro scale is inherently difficult to work according to the second law of thermodynamics. Although the quantitative evaluation of the entropy generation is not made here, it is clearly revealed that the mechanical compressor is the most difficult component to be miniaturized in a micro refrigerator. If a micro vapor compression refrigerator is to be successfully operated, a great deal of efforts must be made to develop a workable micro compressor and to minimize internal heat leak to the evaporator of the refrigerator.